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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2014 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: SelectorSupport.html 939 2015-05-29 01:16:17Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.jsimpledb.kv.raft.net;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import com.google.common.base.Preconditions;<a name="line.10"></a>
<span class="sourceLineNo">011</span><a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.io.IOException;<a name="line.12"></a>
<span class="sourceLineNo">013</span>import java.nio.channels.ClosedChannelException;<a name="line.13"></a>
<span class="sourceLineNo">014</span>import java.nio.channels.SelectableChannel;<a name="line.14"></a>
<span class="sourceLineNo">015</span>import java.nio.channels.SelectionKey;<a name="line.15"></a>
<span class="sourceLineNo">016</span>import java.nio.channels.Selector;<a name="line.16"></a>
<span class="sourceLineNo">017</span>import java.util.ArrayList;<a name="line.17"></a>
<span class="sourceLineNo">018</span>import java.util.Iterator;<a name="line.18"></a>
<span class="sourceLineNo">019</span><a name="line.19"></a>
<span class="sourceLineNo">020</span>import org.slf4j.Logger;<a name="line.20"></a>
<span class="sourceLineNo">021</span>import org.slf4j.LoggerFactory;<a name="line.21"></a>
<span class="sourceLineNo">022</span><a name="line.22"></a>
<span class="sourceLineNo">023</span>/**<a name="line.23"></a>
<span class="sourceLineNo">024</span> * Support superclass for classes that perform NIO selection operations.<a name="line.24"></a>
<span class="sourceLineNo">025</span> */<a name="line.25"></a>
<span class="sourceLineNo">026</span>public abstract class SelectorSupport {<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>    protected final Logger log = LoggerFactory.getLogger(this.getClass());<a name="line.28"></a>
<span class="sourceLineNo">029</span><a name="line.29"></a>
<span class="sourceLineNo">030</span>    /**<a name="line.30"></a>
<span class="sourceLineNo">031</span>     * Create a new {@link SelectionKey} by registering the given channel on the given {@link Selector}<a name="line.31"></a>
<span class="sourceLineNo">032</span>     * and associating the specified {@link IOHandler} to handle I/O ready conditions.<a name="line.32"></a>
<span class="sourceLineNo">033</span>     *<a name="line.33"></a>
<span class="sourceLineNo">034</span>     * &lt;p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span>     * Initially, no I/O operations will be selected. Use {@link #selectFor selectFor()} to add/remove them.<a name="line.35"></a>
<span class="sourceLineNo">036</span>     *<a name="line.36"></a>
<span class="sourceLineNo">037</span>     * @param selector NIO selector<a name="line.37"></a>
<span class="sourceLineNo">038</span>     * @param channel I/O channel<a name="line.38"></a>
<span class="sourceLineNo">039</span>     * @param handler I/O handler<a name="line.39"></a>
<span class="sourceLineNo">040</span>     * @return new selection key<a name="line.40"></a>
<span class="sourceLineNo">041</span>     * @throws IllegalArgumentException if any parameter is null<a name="line.41"></a>
<span class="sourceLineNo">042</span>     * @throws ClosedChannelException if {@code channel} is closed<a name="line.42"></a>
<span class="sourceLineNo">043</span>     */<a name="line.43"></a>
<span class="sourceLineNo">044</span>    protected SelectionKey createSelectionKey(Selector selector, SelectableChannel channel, IOHandler handler)<a name="line.44"></a>
<span class="sourceLineNo">045</span>      throws ClosedChannelException {<a name="line.45"></a>
<span class="sourceLineNo">046</span><a name="line.46"></a>
<span class="sourceLineNo">047</span>        // Sanity check<a name="line.47"></a>
<span class="sourceLineNo">048</span>        Preconditions.checkArgument(selector != null, "null selector");<a name="line.48"></a>
<span class="sourceLineNo">049</span>        Preconditions.checkArgument(channel != null, "null channel");<a name="line.49"></a>
<span class="sourceLineNo">050</span>        Preconditions.checkArgument(handler != null, "null handler");<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span>        // Register channel with our selector<a name="line.52"></a>
<span class="sourceLineNo">053</span>        return channel.register(selector, 0, handler);<a name="line.53"></a>
<span class="sourceLineNo">054</span>    }<a name="line.54"></a>
<span class="sourceLineNo">055</span><a name="line.55"></a>
<span class="sourceLineNo">056</span>    /**<a name="line.56"></a>
<span class="sourceLineNo">057</span>     * Enable or disable listening for the specified I/O operation(s).<a name="line.57"></a>
<span class="sourceLineNo">058</span>     *<a name="line.58"></a>
<span class="sourceLineNo">059</span>     * @param selectionKey selection key; may be null, in which case this method does nothing<a name="line.59"></a>
<span class="sourceLineNo">060</span>     * @param ops I/O operations<a name="line.60"></a>
<span class="sourceLineNo">061</span>     * @param enabled true to enable, false to disable<a name="line.61"></a>
<span class="sourceLineNo">062</span>     */<a name="line.62"></a>
<span class="sourceLineNo">063</span>    protected void selectFor(SelectionKey selectionKey, int ops, boolean enabled) {<a name="line.63"></a>
<span class="sourceLineNo">064</span>        if (selectionKey == null)<a name="line.64"></a>
<span class="sourceLineNo">065</span>            return;<a name="line.65"></a>
<span class="sourceLineNo">066</span>        final int currentOps = selectionKey.interestOps();<a name="line.66"></a>
<span class="sourceLineNo">067</span>        selectionKey.interestOps(enabled ? currentOps | ops : currentOps &amp; ~ops);<a name="line.67"></a>
<span class="sourceLineNo">068</span>    }<a name="line.68"></a>
<span class="sourceLineNo">069</span><a name="line.69"></a>
<span class="sourceLineNo">070</span>    /**<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * Handle any ready I/O operations available from the given {@link Selector}.<a name="line.71"></a>
<span class="sourceLineNo">072</span>     *<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * &lt;p&gt;<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * This assumes an {@link IOHandler} is assocated with each {@link SelectionKey} (e.g., they were created<a name="line.74"></a>
<span class="sourceLineNo">075</span>     * via {@link #createSelectionKey createSelectionKey()}).<a name="line.75"></a>
<span class="sourceLineNo">076</span>     *<a name="line.76"></a>
<span class="sourceLineNo">077</span>     * @param selector NIO selector<a name="line.77"></a>
<span class="sourceLineNo">078</span>     */<a name="line.78"></a>
<span class="sourceLineNo">079</span>    protected void handleIO(Selector selector) {<a name="line.79"></a>
<span class="sourceLineNo">080</span>        for (Iterator&lt;SelectionKey&gt; i = selector.selectedKeys().iterator(); i.hasNext(); ) {<a name="line.80"></a>
<span class="sourceLineNo">081</span>            final SelectionKey key = i.next();<a name="line.81"></a>
<span class="sourceLineNo">082</span>            i.remove();<a name="line.82"></a>
<span class="sourceLineNo">083</span>            final IOHandler handler = (IOHandler)key.attachment();<a name="line.83"></a>
<span class="sourceLineNo">084</span>            if (this.log.isTraceEnabled())<a name="line.84"></a>
<span class="sourceLineNo">085</span>                this.log.trace("I/O ready: key=" + dbg(key) + " handler=" + handler);<a name="line.85"></a>
<span class="sourceLineNo">086</span>            try {<a name="line.86"></a>
<span class="sourceLineNo">087</span>                handler.serviceIO(key);<a name="line.87"></a>
<span class="sourceLineNo">088</span>            } catch (IOException e) {<a name="line.88"></a>
<span class="sourceLineNo">089</span>                if (this.log.isDebugEnabled())<a name="line.89"></a>
<span class="sourceLineNo">090</span>                    this.log.debug("I/O error from " + handler, e);<a name="line.90"></a>
<span class="sourceLineNo">091</span>                handler.close(e);<a name="line.91"></a>
<span class="sourceLineNo">092</span>            } catch (Throwable t) {<a name="line.92"></a>
<span class="sourceLineNo">093</span>                this.log.error("service error from " + handler, t);<a name="line.93"></a>
<span class="sourceLineNo">094</span>                handler.close(t);<a name="line.94"></a>
<span class="sourceLineNo">095</span>            }<a name="line.95"></a>
<span class="sourceLineNo">096</span>        }<a name="line.96"></a>
<span class="sourceLineNo">097</span>    }<a name="line.97"></a>
<span class="sourceLineNo">098</span><a name="line.98"></a>
<span class="sourceLineNo">099</span>    /**<a name="line.99"></a>
<span class="sourceLineNo">100</span>     * Get a debug description of the given keys.<a name="line.100"></a>
<span class="sourceLineNo">101</span>     *<a name="line.101"></a>
<span class="sourceLineNo">102</span>     * @param keys selection keys<a name="line.102"></a>
<span class="sourceLineNo">103</span>     * @return debug description<a name="line.103"></a>
<span class="sourceLineNo">104</span>     */<a name="line.104"></a>
<span class="sourceLineNo">105</span>    protected static String dbg(Iterable&lt;? extends SelectionKey&gt; keys) {<a name="line.105"></a>
<span class="sourceLineNo">106</span>        final ArrayList&lt;String&gt; strings = new ArrayList&lt;&gt;();<a name="line.106"></a>
<span class="sourceLineNo">107</span>        for (SelectionKey key : keys)<a name="line.107"></a>
<span class="sourceLineNo">108</span>            strings.add(dbg(key));<a name="line.108"></a>
<span class="sourceLineNo">109</span>        return strings.toString();<a name="line.109"></a>
<span class="sourceLineNo">110</span>    }<a name="line.110"></a>
<span class="sourceLineNo">111</span><a name="line.111"></a>
<span class="sourceLineNo">112</span>    /**<a name="line.112"></a>
<span class="sourceLineNo">113</span>     * Get a debug description of the given key.<a name="line.113"></a>
<span class="sourceLineNo">114</span>     *<a name="line.114"></a>
<span class="sourceLineNo">115</span>     * @param key selection key<a name="line.115"></a>
<span class="sourceLineNo">116</span>     * @return debug description<a name="line.116"></a>
<span class="sourceLineNo">117</span>     */<a name="line.117"></a>
<span class="sourceLineNo">118</span>    protected static String dbg(SelectionKey key) {<a name="line.118"></a>
<span class="sourceLineNo">119</span>        try {<a name="line.119"></a>
<span class="sourceLineNo">120</span>            return "Key[interest=" + dbgOps(key.interestOps()) + ",ready="<a name="line.120"></a>
<span class="sourceLineNo">121</span>              + dbgOps(key.readyOps()) + ",obj=" + key.attachment() + "]";<a name="line.121"></a>
<span class="sourceLineNo">122</span>        } catch (java.nio.channels.CancelledKeyException e) {<a name="line.122"></a>
<span class="sourceLineNo">123</span>            return "Key[canceled]";<a name="line.123"></a>
<span class="sourceLineNo">124</span>        }<a name="line.124"></a>
<span class="sourceLineNo">125</span>    }<a name="line.125"></a>
<span class="sourceLineNo">126</span><a name="line.126"></a>
<span class="sourceLineNo">127</span>    /**<a name="line.127"></a>
<span class="sourceLineNo">128</span>     * Get a debug description of the given I/O ops.<a name="line.128"></a>
<span class="sourceLineNo">129</span>     *<a name="line.129"></a>
<span class="sourceLineNo">130</span>     * @param ops I/O operation bits<a name="line.130"></a>
<span class="sourceLineNo">131</span>     * @return debug description<a name="line.131"></a>
<span class="sourceLineNo">132</span>     */<a name="line.132"></a>
<span class="sourceLineNo">133</span>    protected static String dbgOps(int ops) {<a name="line.133"></a>
<span class="sourceLineNo">134</span>        final StringBuilder buf = new StringBuilder(4);<a name="line.134"></a>
<span class="sourceLineNo">135</span>        if ((ops &amp; SelectionKey.OP_ACCEPT) != 0)<a name="line.135"></a>
<span class="sourceLineNo">136</span>            buf.append("A");<a name="line.136"></a>
<span class="sourceLineNo">137</span>        if ((ops &amp; SelectionKey.OP_CONNECT) != 0)<a name="line.137"></a>
<span class="sourceLineNo">138</span>            buf.append("C");<a name="line.138"></a>
<span class="sourceLineNo">139</span>        if ((ops &amp; SelectionKey.OP_READ) != 0)<a name="line.139"></a>
<span class="sourceLineNo">140</span>            buf.append("R");<a name="line.140"></a>
<span class="sourceLineNo">141</span>        if ((ops &amp; SelectionKey.OP_WRITE) != 0)<a name="line.141"></a>
<span class="sourceLineNo">142</span>            buf.append("W");<a name="line.142"></a>
<span class="sourceLineNo">143</span>        return buf.toString();<a name="line.143"></a>
<span class="sourceLineNo">144</span>    }<a name="line.144"></a>
<span class="sourceLineNo">145</span><a name="line.145"></a>
<span class="sourceLineNo">146</span>// IOHandler<a name="line.146"></a>
<span class="sourceLineNo">147</span><a name="line.147"></a>
<span class="sourceLineNo">148</span>    /**<a name="line.148"></a>
<span class="sourceLineNo">149</span>     * Callback interface used by {@link SelectorSupport}.<a name="line.149"></a>
<span class="sourceLineNo">150</span>     */<a name="line.150"></a>
<span class="sourceLineNo">151</span>    public interface IOHandler {<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>        /**<a name="line.153"></a>
<span class="sourceLineNo">154</span>         * Handle ready I/O.<a name="line.154"></a>
<span class="sourceLineNo">155</span>         *<a name="line.155"></a>
<span class="sourceLineNo">156</span>         * @param key selection key<a name="line.156"></a>
<span class="sourceLineNo">157</span>         * @throws IOException if an I/O error occurs; this will result in this instance being {@link #close close()}'ed<a name="line.157"></a>
<span class="sourceLineNo">158</span>         */<a name="line.158"></a>
<span class="sourceLineNo">159</span>        void serviceIO(SelectionKey key) throws IOException;<a name="line.159"></a>
<span class="sourceLineNo">160</span><a name="line.160"></a>
<span class="sourceLineNo">161</span>        /**<a name="line.161"></a>
<span class="sourceLineNo">162</span>         * Notification that an exception was thrown by {@link #serviceIO serviceIO()}.<a name="line.162"></a>
<span class="sourceLineNo">163</span>         * Typically this method will close the associated channel, which implicitly unregisters<a name="line.163"></a>
<span class="sourceLineNo">164</span>         * the associated {@link SelectionKey}s.<a name="line.164"></a>
<span class="sourceLineNo">165</span>         *<a name="line.165"></a>
<span class="sourceLineNo">166</span>         * &lt;p&gt;<a name="line.166"></a>
<span class="sourceLineNo">167</span>         * This method must be idempotent.<a name="line.167"></a>
<span class="sourceLineNo">168</span>         *<a name="line.168"></a>
<span class="sourceLineNo">169</span>         * @param cause the error that occurred<a name="line.169"></a>
<span class="sourceLineNo">170</span>         */<a name="line.170"></a>
<span class="sourceLineNo">171</span>        void close(Throwable cause);<a name="line.171"></a>
<span class="sourceLineNo">172</span>    }<a name="line.172"></a>
<span class="sourceLineNo">173</span>}<a name="line.173"></a>
<span class="sourceLineNo">174</span><a name="line.174"></a>




























































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